The art of extracting features from an image, such as an image displayed on a cathode ray tube (CRT), is important in the field of pattern recognition and image processing. In this art, it is becoming increasingly important that such pattern recognition be done rapidly and accurately. To achieve speed and accuracy, the art has turned toward the method of moment generation, which is a familiar function in the art of mechanics. Moments are useful descriptors unique to the shape of a particular image, such as the centroid of the intensity pattern of an image. Unfortunately, known moment generators typically suffer from time inefficiencies related to multiplicative and exponential operation or suffer from being too expensive and complex to integrate onto a circuit chip.
One such moment generation arrangement is disclosed in the publication by M. R. Teague entitled "Optical Calculation of Radiant Moments", Applied Optics, Vol. 19, No. 8, pp. 1354-1356, Apr. 15, 1980. There the arrangement uses mirrors, lenses, beam splitters and photodetectors to optically generate the moments of an image. This arrangement, however, is expensive to implement and suffers from the time consuming problem of aligning the optical apparatus to obtain the moments of the subject image.
Another moment generator arrangement is disclosed in the publication by A. P. Reeves entitled "A Parallel Mesh Moment Computer", IEEE Proceedings of the 6th International Conference on Pattern Recognition, Vol. 1, pp. 465-467. There a triangular matrix of processing elements are used to generate a set of moments of order three. Each processing element in the matrix generates a single moment and includes an arithmetic logic unit and local memory for storing moment values and constant coefficients. This arrangement, however, is also expensive to implement since each processing element is essentially a microcomputer programmed to only generate a single moment.